Simulations of Overhead Irrigation in a Greenhouse Setting Reveal the Potential for Splash Dispersal of Fusarium oxysporum Microconidia

Management of Fusarium wilt of watermelon, caused by the fungus Fusarium oxysporum f. sp. niveum (Fon), requires pathogen monitoring in watermelon production systems. This includes checking for inoculum dispersal in production greenhouses. Fusarium oxysporum f. sp. niveum microconidia were subjected to simulated overhead irrigation to test their capacity for dispersal in a greenhouse setting and evaluate the effect of irrigation drop height on the dispersal patterns. In all trials, a single overhead irrigation event for a single contaminated seedling tray resulted in contamination of all adjacent trays and indicated a potential for microconidia dispersal of more than 70 cm. No difference was detected in spore dispersal patterns based on drop height. The findings of these studies provide possible guidance for scouting protocols and a framework for studies in similar plant disease systems for greenhouse settings.